Chun Young-woo, top secretary to South Korean President Lee Myung-bak for foreign and security affairs, speaks to reporters at the presidential Blue House compound in Seoul October, 7. South Korea has reached a landmark agreement with the United States to extend the range of Seoul's ballistic missiles by more than twice the current limit to counter the threat from North Korea.

SouthKorea has reached a landmark agreement with the United States to extend the range of Seoul's ballistic missiles by more than twice the current limit to counter the threat from North Korea, the government said on Sunday.

The move to significantly boost the South's missile capabilities along with development of advanced aerial reconnaissance vehicles is likely to rattle the communist North, which has remained at odds since the 1950-53 Korean War left the peninsula divided.

It may also stoke concern in China, Japan and Russia, parts of which would be within range of the new missiles.

Under the agreement, SouthKorea can develop missiles up to a range of 800 kms (497 mile) from the current ceiling of 300 kms (186 mile), Chun Young-woo, top secretary to President Lee Myung-bak for foreign and security affairs, told reporters.

He said the United States and SouthKorea also agreed to maintain the maximum payload for a South Korean-developed ballistic missile at the current level of 500 kilograms (1,102 lbs).

However, if Seoul chose to develop a missile with shorter ranges, it could increase the payload accordingly.

SouthKorea has also been allowed to develop unmanned aerial vehicles, or UAVs, with an unlimited payload weight if the flying distance is within 300 kilometres.

Seoul has for years sought to extend its missile range to deter the North, which it said had developed missiles that could reach every corner of the country. It also wanted to increase the payload for the UAVs and develop not only reconnaissance UAVs but also combat drones.

"The most important goal for our government to revise the missile guidelines is deterring North Korea's military provocations," Chun said.

Washington had sought to discourage SouthKorea from developing longer-range ballistic missiles in keeping with a voluntary international arms-control pact known as the Missile Technology Control Regime (MTCR). (Reporting by Sung-won Shim; Editing by Sanjeev Miglani)